Improvement in electro-magnets



E. L. PAINE. Eleot'ro-Magnet,

Patented March 5, 1878.

UNITED STATES PATENT OFFICE.

EDWIN L. PAINE, OF NEWARK, NEW JERSEY, ASSIGNOR TO ANDREW ALLBRIGHT, OF SAME PLACE.

lM PROVEMENT IN ELECTRO-MAGNETS.

Specification forming part of Letters Patent No. 200,929, dated March 5, 1878; application filed October 8, 1877.

To all whom it may concern:

Be it known that I, EDWIN L. PAINE, of the city of Newark, county of Essex, and State of New Jersey, have invented a new and useful Improvement in Electro-Magnets, which improvement is fully set forth in the following specification and accompanying drawing.

The object of my invention is to simplify the construction of that class of electro-magnets required for percussive action (as in dental pluggers, telegraph-sounders, and electromagnetic stencil tools) by increasing the efficiency of magnet, thereby enabling a weak battery to supply, in connection with my magnet, an effect equal to that heretofore attained with a much stronger battery when used with all ordinary magnets; and the accompanying drawing, making part of this specification, is a vertical section of the several parts described, and which, for purpose of illustration, represents the improvement as used in a telegraphsounder.

A soft-iron bobbin, A, wrapped with wire a in the usual way, is set in the bottom of a soft-iron cylinder, B. The axis of the bobbin is traversed by a brass rod, 0, on the head of which is a disk-armature, D, also of soft iron, and on the foot 0 of the rod is secured a spiral spring, d. E E are binding-posts, connecting with the coil around the bobbin.

When the current traverses the bobbin A, the bobbin becomes a magnet of a given polarity by direct action of the current. The lower end of bobbin, resting on the bottom of the cylinder B, by magnetic induction polarizes the upper end of the cylinder, and the cylinder-pole is the opposite of that of the bobbin-pole.

When the circuit is closed, the armature D is 'drawn down and the foot 0 strikes the sounding-plate e and when the circuit opens, the spring at d drives the armature against the adjusting-screw f.

Although it is essential to the successful working of this magnet that the cylinder B should be of soft iron or other material susceptible of magnetic induction, I do not claim the same, broadly, as my invention, but limit myself to the employment of a softiron cylinder differing from that shown in patent to Dexter, No. 186,234, January 16, 1877, dental plugger. IVhile it is found of great advantage to employ about the bobbin a soft-iron cylindrical shell, it is further found to conduce largely to the strength of the magnetic effects to extend the cylindrical shell above the upper portion of the bobbin, thereby completely incasing the armature within the said cylinder, the projecting portions of the shell here covered by a softiron cap; for should the cylinder be of copper or other diamagnetic material, the action of the armature will be weak and sluggish un der a given battery as compared with the iron cylinder; and without any cylinder incasing the bobbin, double the number of cells will be required to actuate the armature that works it with the cylinder.

The upper end of the bobbin should always be free from contact with the cylinder, the space beingatleast one-eighth the diameter of the bobbins head; but the armature may be fitted as closely to the cylinder as it can be, and not induce frictional contact. 1 have made the valuable discovery that the cylinder EDIVIN L. PAINE.

In presence of--- W. M. PAINE, J. G. CLAYTON. 

